Studies on the mechanisms of calcium transport and sodium transport will be undertaken with emphasis on cerebral tissues. Calcium uptake and release will be characterized in metabolically stable mitochondria obtained from rat and guinea pig brains using calcium-sensitive electrodes. The Ca 2 ion stimulated ATPase from brain will be studied. Histochemical studies will be carried out to localize (Na ion, K ion)-ATPase activity in epileptic cortex. We will begin to use liposomal systems for reconstitution experiments using purified ATPase preparations.